For example, various technologies for improving quality of images formed by a video display device including a backlight, such as a liquid crystal display device, have been developed. A technology called local dimming is one of examples of these technologies.
Patent Literature 1 discloses a technology relating to local dimming. Local dimming is a technology which divides a display panel into a plurality of areas, and dims each of a plurality of light sources disposed in corresponding one of the areas in accordance with brightness of an image formed in the corresponding area of the display panel. This technology can increase contrast of images within one screen. Each of the light sources is constituted by a light emitting element such as a light emitting diode (LED), for example.